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Post by pmatulew on Jun 23, 2013 17:59:33 GMT -5
Air flow in/out balance is one thing. Air/fuel balance is another matter. Be careful to keep track so you don't end up running too lean.
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Post by pmatulew on Jun 22, 2013 12:06:13 GMT -5
 Too funny! After all this discussion I was out in the garage this morning looking at my project scoot, (basket case I haven't even had a chance to ride yet), and happened to take a look at the tires. It has a set of Duro's with a definite directional tread pattern and they are both mounted the same way with the sidewall arrow rolling forward! So the front is actually backward! It's getting too hot to work outside, so this afternoon I'll have to flip the front around the other way so I can be technically correct. ;D
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Post by pmatulew on Jun 22, 2013 7:20:04 GMT -5
GEH, the internet is full of arm chair warriors arguing technicalities. i generally try to stay out of the many "mines bigger than yours" contests. At the end of the day, in the really real world, if it's working for you, who's to say it's wrong. As you say, the tread on the 568's is rather vague so it's not that dig of a deal.
Just keep in mind that street tires aren't sand tires. You're not likely to be scooping anything but water, which if you pile up enough of it under your tire is going to cause you to hydroplane.
Doublert, sorry for hijacking your thread. Personally I don't think changing the tire size is going to be much of an improvement. You might gain a few percentage points of top end speed by increasing the outside diameter of your tires, but you will do so at the expense of acceleration at the bottom end and throttle response throughout the mid-range as well as possibly negatively altering the handling of the scoot. (Taller tires on the same rims will feel more wishy washy than lower profile tires.)
If you're really intent on deviating from the stock size I would carefully measure the how much space you have for stuffing a bigger tire on your scoot and then find some place where there are other scoots with mounted tires that you can measure for reference.
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Post by pmatulew on Jun 21, 2013 12:10:29 GMT -5
At the risk of putting my foot in it again.... I must respectfully suggest that your analogy should be the other way around. The rear tire, (the SR568 are listed on the factory webpage as rear tires), should have the tread pattern pointing up as you look at it from the rear, so that the tread pattern is pointing to the rear as it touches the ground. Driving the point rearward into the pavement while accelerating. When mounted as a front tire it should have the tread pattern pointing up as you look at it from the front so that the tread pattern is pointing forward as it touches the ground. Driving the point forward into the ground while braking. www.shinkotireusa.com/product/product.php?id=56 The SR568 don't have a lot of tread directionality to them so it's not easy to tell at first glance which way they should go and it probably doesn't make a huge difference. (The skinnier SR567 have a more obvious pattern) Since the SR568 are listed as rear tires, I would go with the marked rotation arrow (if there is one) when mounted on the rear and do the opposite when mounted on the front. |
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Post by pmatulew on Jun 20, 2013 14:24:31 GMT -5
Hmm. Deep thought after further reflection. I think the source of our disagreement is not about using a specified tire correctly in it's correct place, but rather using a tire on the opposite wheel than it was intended. Most of my experience is on bigger bikes where the tires are not interchangeable so that was never a consideration before. After further research it appears that you are correct.  With a directional tread pattern the front tires are generally marked to account for braking forces and the rears are marked to account for acceleration forces. So if you're using the same tire front and back they should be opposite. Just make sure they are going the right way. Whether you are looking at the back of the bike or the front, the V's of the tread pattern should point up. |
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Post by pmatulew on Jun 20, 2013 12:52:28 GMT -5
Smaller diameter wheels experience the same dynamic forces at lower road speeds as do larger diameter wheels at higher speeds, so that's not a valid argument. But your individual results will really depend more on the manufacturer and the specific way each model of tire was constructed. Sometimes you can get away with it, sometimes you can't.
While I don't doubt that the handling of your ride has improved with a better quality tire, it is more likely due to the construction of the tire carcass and the rubber compound than it is the specific tread pattern. Better rubber will completely transform the handling of a two wheeled vehicle.
As for the rotation direction we will agree to disagree. If it a non-directional tread pattern, do whatever you like. But I must maintain that if the manufacturer put an arrow on it, then it was put there for a reason.
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Post by pmatulew on Jun 20, 2013 12:24:33 GMT -5
Expensive motorcycle specific oils? Two reasons.
1. Most mtorcycle and ATV engines generally have the transmission gears swimming in with the engine oil so extra shearing-force additives are required to inhibit pre-mature breakdown of the oil.
2. Most motorcycle and ATV engines have wet clutches. The multi-plate clutch is swimming in the engine oil. So you need special additives to keep the clutch from slipping too much.
Neither of these factors apply to GY6 CVT motors. So no need to spend extra on the fancy $9/quart stuff. Regular motor oil should do just fine. Petro or synthetic is your call.
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Post by pmatulew on Jun 20, 2013 11:48:48 GMT -5
Low speed circuit too lean or not working. Idle speed adjustment set high to compensate and keep fuel flowing from the main jet. So it's not transitioning back down to the idle jet. DX Check that the slide is free. Check for air leaks. Check that the idle jet is clear. Check the float height. Then start twisting the dials until it behaves correctly.
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Post by pmatulew on Jun 20, 2013 11:36:46 GMT -5
Tire mounted backward = Fail!  Two reasons: #1 - Depending on the construction of the tire, running it backwards can cause the internal structure to come apart. YMMV #2 - More importantly if the tire manufacturer marked it with a particular rotation direction it is likely that the tire has a directional tread pattern (some sort of chevrons like a farm tractor tire). The correct rotation direction will cause the tire to dig in and achieve maximum traction while braking. Turn it around the other way and it will be skittering all over when you need it most. |
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Post by pmatulew on Jun 17, 2013 20:50:17 GMT -5
DX Piston, cylinder, rings, at a minimum. Looks like considerable wear. How many miles on that build?
Gotta figure out what's up with that valve and decide if the head is still okay to use.
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Post by pmatulew on Jun 17, 2013 17:47:41 GMT -5
Vespa for bragging rights. Honda/Yamaha head and shoulders above the rest for reliability. Taiwan scoots (Kymco/Sym) are middle of the road. China scoots are a mixed bag depending on which label they are made for. If you can afford fuel injection, do it. Beginner advice: Get thee to an MSF course --> online2.msf-usa.org/msf/Default.aspx It's the best investment in time and money you can make. You'll learn how to work a clutch and shifter so you can move up to a bigger bike later no problems. You also get your class "M" license rating without needing to take the road test at the DMV. All The Gear (at least 98%) Of The Time. Hat and gloves mandatory. no exceptions, then work up from there depending on your riding conditions and your budget. You don't have to spend a lot to get adequate gear. Convince yourself to get a full face hat. Yes it's more bulky. Yes it's less convenient. You'll get used to it. Anytime you have doubts, just envision a 45 mph face plant on the pavement. That chin bar is there for a reason.  |
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Post by pmatulew on Jun 14, 2013 19:36:10 GMT -5
If you're going to increase the airflow with intake and exhaust mods, then you're definitely going to need to increase the jet size to correct the fuel ratio. Also if you aren't already pre-mixing your oil you may need to consider adjusting the oil pump for more flow or replacing the oil pump cam with something more aggressive. Unless you did it yourself the oil pump probably wasn't adjusted properly to begin with. Not enough oil will roast these little motors in a hurry.
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Post by pmatulew on Jun 12, 2013 17:26:31 GMT -5
Bubbles?
Hoses and tubing at 3:38 -->
Kissing cousins under the skin me thinks.
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Post by pmatulew on Jun 12, 2013 17:06:18 GMT -5
NY DMV doesn't issue titles for 50cc class scooters. They issue a transferable registration. So it really does vary state to state.
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Post by pmatulew on Jun 10, 2013 17:19:02 GMT -5
So, from your description, you have clear fuel lines and the petcock is separate from the fuel tank so it has and in and an out.. You apply vacuum to the vacuum port of the petcock and fuel passes through normally. When you re-connect everything to the motor, the fuel does not get from the petcock to the carburetor?
As a test can you connect the fuel lines as they should be and then apply vacuum to the vacuum port to see if fuel flows through the petcock and fills the carburetor bowl? That would eliminate the possibility any blockage between the petcock and the bowl. Is your fuel tank high mounted so that it should be gravity feed or is it low mounted and there is (or should be) a fuel pump somewhere?
Also cracking the throttle open will actually reduce the intake vacuum since you are allowing ambient air to bypass the throttle plate.
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